Our Rheem heat-pump is on the fritz. It keeps triggering the high-pressure cut-off on the outdoor unit. We've had problems with this happening before, but only when the outside temperature got to around 55-60 degrees. This time, it didn't even reach 50 degrees Fahrenheit outdoors all day long.

So now our heater is running constantly rather than shutting off occasionally like it normally does. It's blowing lukewarm air instead of hot air. I tried resetting the system outside. It runs for a while, but the high-pressure warning goes off after about an hour. Is this problem solvable on my own, or do I need to call in a repair man to have a look?

1 Answer 1


This is a classic sign of low refrigerant. Refrigerant is not a consumable, so low levels indicate a problem. This is not something you can fix yourself. Call a technician, but don't let them just top it off and leave; make them stick around to find the leak.

Since this is a heat pump, the expansion valve is actually a mechanical device and not just a simple orifice like in a regular air conditioner. A failed expansion valve can cause the pressures to be incorrect, mimicking the problem of low refrigerant.

  • I just had a tech look at the system. He said the TXV was bad and in need of replacement. The high pressure reading was 350 and rising when I turned the unit on. He quoted us around $600-$800 to replace it. I'm in southwestern Ohio. Does that sound about right, or are we getting the shaft? Oct 10, 2014 at 23:14
  • 1
    That sounds a bit high, but a bad thermal expansion valve could definitely cause this problem.
    – longneck
    Oct 14, 2014 at 22:47
  • The shop called us with a final estimate of $490 for the repair and a year's warranty on the work. We went ahead and agreed to have the work done. The last thing we need is for the system to fail completely when it gets colder... Oct 16, 2014 at 1:27

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